ttwrplus: Implement power control on SA8x8

Implemented power control in T-TWR Plus by using the embedded switch
(RADIO_PWR) that controls the H/L pin of the SA868.

TG-553

platform/drivers/baseband/SA8x8.c

@@ -40,11 +40,13 @@
 #endif
 
 #define RADIO_PDN_NODE DT_ALIAS(radio_pdn)
+#define RADIO_PWR_NODE DT_NODELABEL(radio_pwr)
 
 #define SA8X8_MSG_SIZE 32U
 
 static const struct device *const uart_dev = DEVICE_DT_GET(UART_RADIO_DEV_NODE);
 static const struct gpio_dt_spec radio_pdn = GPIO_DT_SPEC_GET(RADIO_PDN_NODE, gpios);
+static const struct gpio_dt_spec radio_pwr = GPIO_DT_SPEC_GET_OR(RADIO_PWR_NODE, gpios, {0});
 
 K_MSGQ_DEFINE(uart_msgq, SA8X8_MSG_SIZE, 10, 4);
 
@@ -149,6 +151,21 @@ int sa8x8_init()
         return ret;
     }
 
+    // Initialize GPIO for SA868S high power mode
+    if(gpio_is_ready_dt(&radio_pwr) == false)
+    {
+        printk("SA8x8: error, high power GPIO %s is not ready\n", radio_pdn.port->name);
+        return ret;
+    }
+
+    ret = gpio_pin_configure_dt(&radio_pwr, GPIO_OUTPUT);
+    if (ret != 0)
+    {
+        printk("SA8x8: error %d, failed to configure %s pin %d\n", ret,
+               radio_pwr.port->name, radio_pwr.pin);
+        return ret;
+    }
+
     // Reset the SA868S baseband
     gpio_pin_set_dt(&radio_pdn, 1);
     delayMs(100);
@@ -254,6 +271,17 @@ int sa8x8_enableHSMode()
     return 0;
 }
 
+void sa8x8_setTxPower(const float power)
+{
+    char buf[SA8X8_MSG_SIZE] = { 0 };
+
+    // TODO: Implement fine-grained power control through PA_BIAS SA8x8 register
+    uint8_t amp_enable = (power > 1.0f) ? 1 : 0;
+    int ret = gpio_pin_set_dt(&radio_pwr, amp_enable);
+    if(ret != 0)
+        printk("SA8x8: failed to enable high power mode");
+}
+
 void sa8x8_writeAT1846Sreg(uint8_t reg, uint16_t value)
 {
     char buf[SA8X8_MSG_SIZE];

platform/drivers/baseband/SA8x8.h

@@ -55,6 +55,13 @@ const char *sa8x8_getFwVersion();
  */
 int sa8x8_enableHSMode();
 
+/**
+ * Set the transmission power.
+ *
+ * @param power: transmission power in Watt.
+ */
+void sa8x8_setTxPower(const float power);
+
 /**
  * Write a register of the AT1846S radio IC contained in the SA8x8 module.
  *

platform/drivers/baseband/radio_ttwrplus.cpp

@@ -19,6 +19,7 @@
  ***************************************************************************/
 
 #include <interfaces/radio.h>
+#include <algorithm>
 #include <pmu.h>
 #include "radioUtils.h"
 #include "AT1846S.h"
@@ -129,6 +130,10 @@ void radio_enableTx()
 {
     if(config->txDisable == 1) return;
 
+    // Constrain output power between 1W and 5W.
+    float power  = std::max(std::min(config->txPower, 5.0f), 1.0f);
+    sa8x8_setTxPower(power);
+
     at1846s.setFrequency(config->txFrequency);
     at1846s.setFuncMode(AT1846S_FuncMode::TX);
 

platform/targets/ttwrplus/pmu.cpp

@@ -99,6 +99,8 @@ void pmu_init()
     // Set VSY off voltage as 2600mV , Adjustment range 2600mV ~ 3300mV
     PMU.setSysPowerDownVoltage(2600);
 
+    // High transmit power may cause voltage dropoff, disable PMU protection
+    PMU.disableDC3LowVoltageTurnOff();
 
     //! DC1 ESP32S3 Core VDD , Don't change
     // PMU.setDC1Voltage(3300);